Force Blender to Select rig instead of geometry
For cases like this, I just switch to wireframe shading with Z, select the armature (which is now visable) then switch back to solid shading, again with Z.



Or you can turn off viewport selection, then you will not be able to select the mesh in the 3D view (you can still select it from the outliner).




Another option is to select the armature differently. AltRMB  on your armature, that will bring up a list of objects that is below the mouse. You can pick your armature from that list.